The present invention relates to a noise damper for pneumatic tire which is disposed in a tire hollow and secured to a wheel rim.
In recent years, as the mechanical noise from automobiles especially passenger cars is greatly reduced, the tires especially passenger car tires are strongly required to reduce their noise. There are many factors in the tire noise, but a circumferential resonance of the air in the annular tire hollow is a major factor. That is, a ring of air inside the tire continuous around the rim is excited by vibrations during running and resonates in the circumferential direction. Usually, a resonance peak occurs in a frequency range of from 50 to 400 Hz according to the tire size.
In the published Japanese patent JP-B-7-14682, an assembly of a wheel rim and a pneumatic tire mounted thereon is disclosed, wherein a ball-like body which is made of rubber, sponge or the like is put in the annular tire hollow to block the circumferential continuity thereof to control resonance. Such a ball-like body is however, liable to disturb the high-speed rotational balance of the tire because the inner surface of the tire receives a full gravity of the ball-like body which increases as the rotational speed increases. Further, it has a tendency to make it difficult to mount the tire on a wheel rim.